<dependency>
  <groupId>org.apache.tika</groupId>
  <artifactId>tika-core</artifactId>
  <version>1.20</version>
</dependency>

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.extern.slf4j.Slf4j;
import org.apache.tika.metadata.HttpHeaders;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.metadata.TikaMetadataKeys;
import org.apache.tika.parser.AutoDetectParser;
import org.apache.tika.parser.ParseContext;
import org.xml.sax.helpers.DefaultHandler;
 
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.util.HashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
/**
 * tika
 *
 * @author zhy
 */
@Slf4j
public class TikaToolUtil {
 
  /**
   * 獲取類型
   *
   * @param file 文件
   * @return String
   */
  public static String getMimeType(File file) {
    if (file.isDirectory()) {
      return "the target is a directory";
    }
 
    AutoDetectParser parser = new AutoDetectParser();
    parser.setParsers(new HashMap<>());
    Metadata metadata = new Metadata();
    metadata.add(TikaMetadataKeys.RESOURCE_NAME_KEY, file.getName());
    try (InputStream stream = new FileInputStream(file)) {
      parser.parse(stream, new DefaultHandler(), metadata, new ParseContext());
    } catch (Exception e) {
      log.error(e.getMessage());
    }
    return metadata.get(HttpHeaders.CONTENT_TYPE);
  }
 
  /**
   * 判斷是否是圖片
   *
   * @param file 文件
   * @return boolean
   */
  public static boolean isImage(File file) {
    String type = getMimeType(file);
    System.out.println(type);
    Pattern p = Pattern.compile(Type.IMAGE.name);
    Matcher m = p.matcher(type);
    return m.matches();
  }
 
  /**
   * 判斷是否是zip
   *
   * @param file 文件
   * @return boolean
   */
  public static boolean isZip(File file) {
    String type = getMimeType(file);
    System.out.println(type);
    Pattern p = Pattern.compile(Type.ZIP.name);
    Matcher m = p.matcher(type);
    return m.matches();
  }
 
  /**
   * 判斷是否是dicom
   *
   * @param file 文件
   * @return boolean
   */
  public static boolean isDicom(File file) {
    String type = getMimeType(file);
    Pattern p = Pattern.compile(Type.DCM.name);
    Matcher m = p.matcher(type);
    return m.matches();
  }
 
  /**
   * 類型枚舉
   */
  @Getter
  @AllArgsConstructor
  public enum Type {
    /**
     * dcm
     */
    DCM("application/dicom"),
    /**
     * zip
     */
    ZIP("application/zip"),
    /**
     * 圖片
     */
    IMAGE("image/.*"),
    /**
     * 視頻
     */
    VIDEO("video/*");
 
    private String name;
  }
 
  public static void main(String[] args) {
    boolean image = isImage(new File("C:\\Users\\zhy\\Desktop\\dcm\\123.dcm"));
    System.out.println("zhy:" + image);
  }
}

import java.io.FileInputStream;

public class FileType{
  public static String bytesToHexString(byte[] src) {
    StringBuilder stringBuilder = new StringBuilder();
    if (src == null || src.length <= 0) {
      return null;
    }
    for (int i = 0; i < src.length; i++) {
      int v = src[i] & 0xFF;
      String hv = Integer.toHexString(v);
      if (hv.length() < 2) {
        stringBuilder.append(0);
      }
      stringBuilder.append(hv);
    }
    return stringBuilder.toString();
  }

  /**
   * @param args
   */
  public static void main(String[] args) throws Exception {
    FileInputStream is = new FileInputStream("F:\\相冊\\微信圖片\\03.jpg");
    byte[] b = new byte[3];
    is.read(b, 0, b.length);
    String xxx = bytesToHexString(b);
    xxx = xxx.toUpperCase();
    System.out.println("頭文件是：" + xxx);
    String ooo = TypeDict.checkType(xxx);
    System.out.println("后綴名是：" + ooo);

  }  
}

public class TypeDict {
/**
 常用文件的文件頭如下：(以前六位為準)
JPEG (jpg)，文件頭：FFD8FF 
PNG (png)，文件頭：89504E47 
GIF (gif)，文件頭：47494638 
TIFF (tif)，文件頭：49492A00 
Windows Bitmap (bmp)，文件頭：424D 
CAD (dwg)，文件頭：41433130 
Adobe Photoshop (psd)，文件頭：38425053 
Rich Text Format (rtf)，文件頭：7B5C727466 
XML (xml)，文件頭：3C3F786D6C 
HTML (html)，文件頭：68746D6C3E 
Email [thorough only] (eml)，文件頭：44656C69766572792D646174653A 
Outlook Express (dbx)，文件頭：CFAD12FEC5FD746F 
Outlook (pst)，文件頭：2142444E 
MS Word/Excel (xls.or.doc)，文件頭：D0CF11E0 
MS Access (mdb)，文件頭：5374616E64617264204A 
WordPerfect (wpd)，文件頭：FF575043 
Postscript (eps.or.ps)，文件頭：252150532D41646F6265 
Adobe Acrobat (pdf)，文件頭：255044462D312E 
Quicken (qdf)，文件頭：AC9EBD8F 
Windows Password (pwl)，文件頭：E3828596 
ZIP Archive (zip)，文件頭：504B0304 
RAR Archive (rar)，文件頭：52617221 
Wave (wav)，文件頭：57415645 
AVI (avi)，文件頭：41564920 
Real Audio (ram)，文件頭：2E7261FD 
Real Media (rm)，文件頭：2E524D46 
MPEG (mpg)，文件頭：000001BA 
MPEG (mpg)，文件頭：000001B3 
Quicktime (mov)，文件頭：6D6F6F76 
Windows Media (asf)，文件頭：3026B2758E66CF11 
MIDI (mid)，文件頭：4D546864 
*/
  public static String checkType(String xxxx) {
    
    switch (xxxx) {
    case "FFD8FF": return "jpg";
    case "89504E": return "png";
    case "474946": return "jif";

    default: return "0000";
    }
  }
}